Biology May Cause Us to Hate Exercise, Study Says

Can't keep your exercise resolution? It might be biology's fault. A new study from Interdisciplinary Institute for Neuroscience in Paris has found that a protein in the brain determines how long each person is willing to put up with voluntary exercise.

Neuroscientists have long understood the importance of the brain's endocannabinoid system. Triggered in athletes during exercise, it causes them to experience pleasure (the endocannabinoid system is also stimulated by the main ingredient in marijuana). But in this recent study published in Biological Psychiatry, researchers blocked the CB1 cannabinoid receptor in mice, the part of the brain involved in our feeling motivation and seeking rewards. Those altered mice spent between 20 and 30 percent less time on their exercise wheels than their normal counterparts. When the mice did exercise, scientists were able to see that exercise stimulated the motivation part of the brain (the CB1 cannabinoid receptors) and let the feel-good chemical dopamine flow freely, acting as a reward. The more the normal mice exercised, the more they were rewarded, motivating them more.

Researchers think the same thing happens in humans. People who have more of the motivational chemicals in their bodies feel rewarded more by exercise, so they keep doing it. That means if you don't enjoy yourself while you're exercising, it may just be because you're not wired to. Of course, that doesn't mean give up on exercise together. Get motivated with a friend or try group classes to override that pesky bit of biology.